Atmospheric pressure (AP) plasma may be utilized to remove a coating of material (or layer, film, paint, etc.) from the surface of a substrate. The source of the AP plasma may be a device configured to discharge an AP plasma plume from a nozzle. The device may positioned at some specified distance between the nozzle and the surface of the coating, and oriented so as to direct the AP plasma plume toward the coating. While the AP plasma plume is active, the device may be moved across the coating along an appropriate path. Alternatively, other types of non-plasma chemical etchants (e.g., wet etchants) may be employed to remove the coating from a substrate. Conventionally, the plasma or other chemical etchant is utilized to attack the coating in a top-down removal process, i.e., starting with exposure to the uppermost (exposed) surface of the coating and etching/removing in the downward direction of the thickness of the coating until the underlying substrate is reached. The top-down removal process may be effective in many applications, but is hampered by the fact that all of the coating (its entire volume and thickness) must be etched in order to reach the substrate and completely remove the coating from the substrate. This may take considerable time depending on the thickness of the coating and the relative etch rate of the plasma or chemical etchant.
Another known technique for removing a coating from a substrate involves utilizing a physical scraper or blade to delaminate the coating layer from the substrate. However, physical cutting or scraping is often considered inferior to plasma- and etchant-based techniques. For instance, this technique may be ineffective if the force of the blade impinging on the coating fails to overcome the strength of the adhesive bond strength of the coating to the substrate. The coating may also flake off or shear in the bulk of the coating layer, leaving behind a partially removed coating of uneven profile. The use of intense pressure on the blade may lead to damage to the substrate and may still leave behind coating residue.
In view of the foregoing, there is a need for improved apparatus and methods for efficiently and effectively removing various types of materials from substrates without being impaired by problems attending known techniques.